How to add the file to a calendar
Google Calendar: on a computer, open Settings, choose Import and export, select the downloaded file, and pick a calendar.
Apple Calendar: open the downloaded file on a Mac, iPhone, or iPad and choose Add All.
Outlook: open the downloaded file, or use Add calendar, then Upload from file.
Changed a bill later? Download a new file and import it again. Most calendars update the matching events instead of adding duplicates, but some add a second copy, so it can help to delete the old ones first.